robertp wrote:1. There's two main choices, one from the Core Audio and one from libsndfile. Which one do I want?

2. In the Encoder settings, there's a drop-down menu. Choices. Same question: which?

Use Core Audio. The other's likely there for backwards-compatibility, as it mentions SGI - are Silicon Graphics still going?

Whatever Core Audio is turning out will be compatible with other software on OS X - iTunes for burning. etc.

3. Followup on #2. The options quality, bitrate and VBR ae greyed out. The "quality" one is set to minimum,which troubles me. Clarification?

They're greyed out because they're not relevant because the format is not a lossy format.

I will be wanting to use the AIFF files to burn music cds.

They'd be fine for the purpose. Apple Lossless would be equally as good but take up less room on disk. AIFF is uncompressed audio. Apple Lossless is compressed, but the compression is lossless not lossy - as its name implies. iTunes can uncompress them to burn CD-Player-compatible CDs.

For that select MPEG4 Audio (top one), then "Apple Lossless". Again there's no bitrate setting, because you're not dealing with a lossy format.